The invention relates to a coupling for connecting a double valve defining an axis and placed on a pressure container containing pressure gas, such as CO2, and liquid, such as beer, to a pressure-gas source and a tap for drawing the liquid, respectively, whereby the valve comprises a blockable gas and liquid passage, respectively, and the coupling comprises a housing for coaxial mounting on an upper flange on the valve; a slide which is placed in the housing and which can be displaced by means of a hand grip between an upper position where the valve is closed and a lower position where the valve is open, an elastomeric sleeve secured onto the slide and forming sealing between the slide and the valve flange in the mounted position of the coupling, a tubular plunger secured in the slide; and a gas chamber formed between the plunger, the sleeve, and an inner wall in the slide; whereby the plunger serves to open the valve in the lower position of the slide so that a connection is made between the liquid passage of the valve and a liquid outlet on the slide via the chamber of the plunger, and a connection is made between the gas passage of the valve and a gas outlet on the slide via the gas chamber.
GB Patent No. 1 239 908 discloses such a coupling. In this case, a metal pipe is placed in the gas chamber of the coupling; the pipe is secured to the bottom of the elastomeric sleeve of the coupling by means of an outwardly directed flange. The metal pipe extends upwards along the inner side of the sleeve and has an inwardly directed collar abutting against an elastomeric ring in an annular groove in the plunger in the dismantled position of the coupling. During mounting, the sleeve is compressed whereby the inwardly directed collar of the metal pipe is lifted from its abutment on the elastomeric ring so that there is opened for inlet of gas to the gas passage of the valve and thereby to the pressure container. The object of this structure is to eliminate the possibility of gas flowing out of a dismantled coupling.
However, this structure is complicated and expensive as it is made up of several components and in addition to this the sealing effect is unsafe in the dismantled position of the coupling. The latter is especially due to the fact that the elastomeric ring is inserted loosely in a groove in the plunger, and leaks can be formed between the plunger and the projecting elastomeric ring when the metal pipe affects this ring with a moment thatxe2x80x94seen in cross-sectionxe2x80x94is likely to distort the elastomeric ring. The moment is caused by the quite considerable, in proportion to the structure, axial forces that are generated due to the building up of gas pressure in the gas chamber and the decompression of the sleeve, and that are transmitted to the elastomeric ring via the metal pipe.
The structure furthermore means that the metal pipe must extend upwardly in the gas chamber and the already narrow passage area is therefore further reduced. In order to allow the gas to pass, the metal pipe must furthermore be so fragile that it will contribute to making the sealing between the elastomeric ring and the inwardly directed collar of the metal pipe unsafe in a dismantled coupling.
The object of the invention is to show a coupling of the kind mentioned in the opening paragraph that, with a simple and inexpensive structure, provides a better guarantee against gas outflow when the coupling is dismantled than known so far.
The novel and unique features according to the invention, whereby this is achieved, is the fact that a seat for a sealing ring is made in one piece with the plunger, the sealing ring is made in one piece with the sleeve which is furthermore arranged in such a way that the sealing ring is lifted free of the seat in the mounted condition of the coupling, and abuts against the seat in the dismantled condition of the coupling. This structure does not require any extra components and there are no loose parts. It is therefore inexpensive to manufacture and forms a safe and effective sealing for the pressure gas when the coupling is dismantled.
In an especially simple embodiment, an outwardly directed collar can be made on the lower pressure foot on the plunger for activating the valve; the top side of the collar forms a seat for the sealing ring.
Above the seat, the plunger can furthermore have a first, preferably cylindrical section and in continuation of this, a second, preferably cylindrical section with a smaller diameter than the first section. In dismantled condition of the coupling, the sealing ring can then advantageously enclose the first cylindrical section in contact with or at a short distance from this when the coupling is dismantled and the sealing ring abuts against the seat on the plunger. The result of this is that the first cylindrical section in co-operation with the sealing ring will contribute to seal against outflowing gas when the coupling is dismantled.
The sleeve can furthermore be arranged in such a way that it is deformed when the coupling is mounted and thereby its sealing ring is axially displaced past the first cylindrical section on the plunger whereby the free passage area for the gas is increased.
By forming the elastomeric sleeve with a cross section having a V-shape with radially, outwardly directed point, the sleeve obtains an advantageously flat compressibility characteristic allowing for a considerable, axial compression of the sleeve without at the same time a great increase of the forces used to compress the sleeve.
An effective and safe sealing between the slide and the valve flange is obtained if the sleeve furthermore has a downwards converging sealing lip under the sealing ring.
The sealing ring which is made in one piece with the elastomeric sleeve can advantageously be stabilised and stiffened by an inserted reinforcing ring of e.g. stainless steel.
When the coupling is dismantled, liquid in the plunger chamber can run or drip out and pollute the surroundings. In order to avoid this disadvantage, the pressure foot can have an inwardly directed collar forming a seat for a non-return flap placed in the tubular plunger together with a superjacent compression spring to keep the non-return flap abutting against said seat. The non-return flap functions as a non-return valve during operation but is closed for reflux when the coupling is dismantled.
Conventionally, the liquid outlet is lead axially out through the housing, but in an advantageous embodiment according to the invention, the liquid outlet together with the gas inlet is lead sideways out through an axially extending mortise in the side wall of the housing. Thereby, an expedient piping to the gas source and the barrel tap with an attractive appearance is obtained. At the same time, the chamber in the housing above the slide is left free for the hand grip.
The hand grip can furthermore be pivotally mounted about a swing axis in the housing and be made to run with pressure pins across curved pressure surfaces on each side of the slide when the hand grip is pressed down whereby the pressure surfaces have such a form that the pins at first drive the plunger down to mounted position for finally locking the hand grip.
The pressure surfaces can furthermore be formed as the lower side of curved tracks placed on each side of the slide serving for guides for the pressure pins. In order to be able to lead the pressure pins down to engage with these guide tracks, axial introduction tracks can be made that extend from the guide tracks to the top side of the slide.
A conventional coupling has a centrally placed compression spring for holding the slide in its upper position. The coupling according to the invention can instead have at least one extension spring acting between the housing and the slide, the extension spring is displaced radially relative to the axis of the housing so that the handle grip can swing across this axis and thereby obtains an expedient placing of the angle over which the hand grip can swing.
The invention will be explained in greater detail below, describing only an example of an embodiment with reference to the drawing, in which